If you haven’t been to the Carpinteria salt marsh in a while, this is a great time to visit. The chaparral mallow (Malacothamnus fasciculatus) is in bloom, making the walk to the amphitheater a fairly surreal experience:
I traded docent shifts with Rob Denholtz this month, so I was there on the third Saturday in July, rather than my usual second Saturday. No one showed up for the tour, though, so I took a stroll through the marsh myself, and was rewarded by a breathtaking profusion of purple flowers.
I’m on record as having a crush on coyote brush (Baccharis pilularis). Linda attended a recent talk by Carol Bornstein, author of Reimagining the California Lawn, and Linda told me coyote brush was among the plants Bornstein discussed.
Bornstein wrote in her book about coyote brush’s “utilitarian” character, and Linda said she called it “fairly drab” during her talk, which of course makes me want to rise to its defense. But I admit that its flowers are not the showiest.
Chaparral mallow is another story. If I have a crush on coyote brush, I felt a temporary transfer of affections to chaparral mallow as I walked past the wall of flowers at the marsh. You really should visit while they’re in bloom.
I don’t have any particularly good idea what made this trail. I think I might be seeing a double line, possibly with three sets of footprints outside them:
I previously corresponded with Charley Eiseman (co-author of Tracks & Signs of Insects and Other Invertebrates) about how neat it would be if there was a site like bugguide.net, but focused on tracks and signs. I’m thinking of taking that on; it sounds like it would not be too difficult to set up such a site using Drupal, which I gather is the tool they used to create bugguide.net. I’m not sure I want to take on another project, but it would be awfully neat to have access to a site like that.
Last Saturday I was able to bird the “middle” portion of the Carpinteria salt marsh (normally inaccessible to outside visitors). Even better, I got to go in with Peter Gaede and Andrea Adams-Morden, two of my favorite people when I want to learn more about birds or plants (respectively). That’s damning with faint praise, though, in that Peter and Andrea are just fun to be with. They’re interested in everything going on in the natural world, always noticing things and always happy to share what they’ve noticed.
We entered on Estero Way, and worked our way out to the mouth of the marsh. Then we retraced our steps, and wrapped around next to the railroad tracks until we could walk out along the dike on the west side of the Santa Monica Creek channel. Toward the southern end of the dike there is a large patch of an invasive non-native with tall spindly stalks; Andrea tentatively ID’d it as black mustard (Brassica nigra). Here’s a shot looking past one of those stalks back toward the northwest:
I took that photo because Andrea had notice something interesting in the plant. Here’s a closer view:
It’s a collection of six spherical objects suspended in a loose web; Andrea’s guess was that they were spider egg sacs. Here’s a close-up:
There was one more interesting thing we noticed: Where the stem holding the spheres met the main stalk of the plant, there was a triangular structure that appeared to be made from the same silk as the web. You can see it on the left side of this picture:
Here’s a close-up:
We couldn’t find any spider to go with the putative egg cases, but after I got home I posted photos on bugguide.net, and within 15 minutes Charley Eiseman, co-author of the upcoming book Tracks & Sign of Insects & Other Invertebrates (which I can’t wait to buy) had ID’d the spheres for me. They are indeed the egg cases of a spider, specifically the Bolas spider Mastophora cornigera.
The spider is nocturnal; it hides in plain site during the day by looking exactly like a rounded bird dropping. (When I mentioned that to Andrea, she replied that she actually had noticed what she thought was a bird dropping on the plant not far from the egg sacs. I didn’t notice it at the time, and I can’t find it in any of my photos, unfortunately.)
The spider also has an interesting way of hunting: It dangles a strand of silk with a sticky ball on the end, and swings it with one of its legs to capture flying insects. The ball gives off a scent that mimics moth pheromones, and researchers have found that the spider can vary the scent over the course of an evening to appeal to different moth species that are active at different times of night.
Here’s a segment from David Attenborough’s Life in the Undergrowth showing M. cornigera hunting:
One mystery I still haven’t solved: What was that triangular silk structure at the base of the stem? I tried sending an email to Peter Bryant, a biologist at UC Irvine who has posted some neat photos of Bolas spiders on the web. I wrote him as follows:
I came across what I believe are some Mastophora cornigera egg cases yesterday at the Carpinteria Salt Marsh. I’m curious about one thing, though: There was an odd triangular structure, apparently built out of spider silk, at the point where the stem from which the egg sacs are suspended meets the main stalk of the plant. You can view a photo of the structure in relation to the egg sacs here:
At first I was thinking the structure might be a hiding place for the spider, but now that I’ve had some help identifying the species, and have looked at the wonderful photos you’ve posted of the adult female, I don’t think that structure would be large enough to hide one (and it doesn’t sound like they go in for that sort of thing, anyway, given their impressive bird-dropping mimicry).
I’m trying to figure out what purpose that structure might have. My lay speculation so far consists of:
* The aforementioned hiding place for the adult spider.
* A structural reinforcement, to prevent the weight of the egg sacs from causing the stem to break off the plant.
* A barrier to help prevent egg-sac predators from traveling from the stalk to the stem.
I’m curious if you know the answer, or would be willing to speculate. Thanks!
Dr. Bryant wrote me back, but unfortunately he didn’t have any ideas about that triangular silk structure. He suggested visiting the location again to see if the spider is nearby, which I’d love to do, but so far I haven’t had a chance (and I’d need to go with Peter, or someone else with official permission to enter that part of the marsh).
The chaparral mallows (Malacothamnus fasciculatus) were really in bloom at the salt marsh a month or so ago, when I snapped this photo of a particularly attractive set of flowers. There still are a few mallow flowers here and there at the marsh, but lately it’s the coyote brush (Baccharis pilularis) that has been catching my eye. I think it’s interesting how there are male and female coyote brush plants, with each gender having its own, specific kind of flower. I’ll try to get some photos of those the next time I’m at the bluffs or the marsh.
Linda was the one who taught me to pay attention to the tide. Low tide is her favorite time to check out the rocks at Tar Pits, or walk the beach to the marsh entrance at Sand Point. If the tide is high, she’s not really interested.
But high tide is a great time to visit the marsh. I took a walk there last weekend, and timed it to coincide with maximum high tide. It was a 6.3; that is, the water’s surface was 6.3 feet above Mean Lower Low Water (MLLW). A 6.3 isn’t as high as it gets; at new moon a couple of days later (a couple of days ago, now, as I write this), the tide got up to 7.2.
At 7.2 pretty much all the low marsh habitat, which is dominated by pickleweed (Salicornia virginica), is underwater. Here’s a shot I got last weekend of some pickleweed taking its saltwater bath:
It’s a neat trick for a plant: being able to live in the open air, while also being able to survive immersed in seawater for hours at a time. The high marsh plants, like saltbush, ragweed, mugwort, and sagebrush, can handle a lot, but immerse them in salt water and they’re history.
Because of the tide, the marsh’s plant communities are vertically stratified, and once you learn to look for it it’s really obvious. Going from lowest to highest, the marsh’s major communities are:
Eelgrass beds – Below the lowest of low tides, in the bottoms of the channels that wind through the marsh, is eelgrass. These are strictly aquatic plants.
Mud flats – A little higher, in the intertidal zone, are the mud flats. Not much in the way of visible vegetation lives here, but there’s lots of decaying detritus. There are also microorganisms that feed on it, and lots of invertebrates, and aquatic vertebrates (like fish) and terrestrial vertebrates (like shorebirds) that take turns exploiting the flats as the water rises and falls.
Low marsh – This is the area where the pickleweed reigns supreme. Most of the time this community is above the waterline, but twice a day the high tide soaks its lower reaches, and twice a month (at the time of new and full moon) the high tide goes all the way to the top, killing any would-be invaders from the high marsh, and maintaining the boundary, as level as if it were layed out by a surveyor, between the two communities.
High marsh – A wider assortment of plants, tolerant of the high salt levels in the marsh soil, but incapable of actually being immersed.
There’s something else that happens during the highest tides in the marsh: Aquatic predators (like fish) invade the inundated area, picking terrestrial insects off the pickleweed stems. I’d love to see that.